The 33-year-old made a number of vital saves for the struggling Premier League side in Saturday's 1-1 draw with West Ham United.
"He's a world-class keeper," Redknapp told the club's official website. "You look at his CV and it's absolutely remarkable.
"He's won absolutely everything there is to win in the game and he's still relatively young for a keeper. He's world-class. A top, top goalkeeper."
Cesar moved to Loftus Road on a four-year contract from Inter Milan last summer.